Preheat oven to 350°.
Cook sliced potatoes in boiling, salted water for 15 minutes.
In saucepan, combine soups, sour cream and dehydrated onion, mixing well and until thoroughly heated.
In large casserole, layer potatoes, soup mixture, cheese and repeat.
Bake for 20 to 30 minutes, until cheese is bubbly.
Great served with meatloaf or ham.